Nano-imprinting lithography is a promising technique for obtaining nano-size (as small as a few tens of nanometers) patterns. A key step in forming the nano-size patterns is to first form an imprint stamp (also called an imprinting stamp) that includes a pattern that complements the nano-sized patterns that are to be imprinted by the imprint stamp.
Prior imprint stamps include those made using a micro-casting technique as depicted in FIGS. 1A and 1B, wherein a mold layer 201 is photo lithographically patterned and then etched (e.g. using an anisotropic etch) to form a cavity 201m extending inward of a surface 201s of the mold layer 201. As a result, the cavity 201m includes a minimum feature size λL that is greater than or equal to a lithography limit of a lithographic system that was used to pattern the cavity 201m. The cavity 201m may however have a feature depth dm that can be lower than the minimum feature size λL. For example, the minimum feature size λL can be limited by a wavelength of light used to expose the mask layer 201 through a photo mask as is well understood in the microelectronics art.
In FIGS. 2A and 2B, a feature layer 203 is deposited on the mold layer 201 and fills in the cavity 201m so that a feature 203f connected with the feature layer 203 is formed in the cavity 201m. Because the cavity serves as a mold for the feature 203f, the feature 203f also includes the minimum feature size λL. The feature layer 203 can be planarized so that it includes a substantially planar upper surface 203s. 
In FIGS. 3A and 3B, a glue layer 205 can be deposited on the substantially planar upper surface 203s in preparation for a wafer bonding process. In FIGS. 4A and 4B, a handling wafer 207 is urged into contact with a surface 205s of the glue layer 205 and heat H and pressure P are applied to the handling wafer 207 and the mold layer 201 to bond a bottom surface 207b of the handling wafer 207 with the glue layer 205.
In FIGS. 5A and 5B, the feature layer 203 and the features 203f are released from the mold layer 201 using an etching process to dissolve the mold layer 201 or a back-grinding process extract an imprint stamp 200.
One disadvantage to the prior imprint stamp 200 is that the features 203f include the minimum feature size λL. Accordingly, if it is desired to imprint features that are less than the minimum feature size λL, then the features 203f will not be efficacious for that purpose because the smallest dimension of the features 203f is at least equal to or greater than the minimum feature size λL.
Another disadvantage of the prior imprint stamp 200 is that the features 203f are susceptible to wearing out and therefore losing their micro-casted shape due to repeated imprinting operations. As an example, in FIG. 5B, if the feature layer 203 is made from a relatively soft material such as silicon (Si), then edge portions 203e of the features 203f are susceptible to wear W when the prior imprint stamp 200 is repeatedly pressed into contact with a media (not shown) to be imprinted with an imprint pattern defined by the features 203f. Consequently, the imprint pattern will wear out thereby reducing the accuracy of the pattern that is imprinted or the features 203f will be damaged. In either case, the useful lifetime of the prior imprint stamp 200 is reduced.
Because fabrication of the prior imprint stamp 200 is one of the most crucial and most expensive steps in the entire imprinting lithography process, another disadvantage of the prior imprint stamp 200 is that a cost of manufacturing the imprint stamp 200 is not recouped because the imprint stamp 200 is damaged and/or wears out before an adequate number of pressing steps required to justify the manufacturing cost of the imprint stamp 200 can occur. Accordingly, the prior imprint stamp 200 is not economical to manufacture.
Consequently, there exists a need for an imprint stamp made from a resilient material that is resistant to wear, damage, and breakage. There is also an unmet need for an imprint stamp that can retain consistent, repeatable, and accurate imprint patterns over multiple pressing steps so that the cost of manufacturing the nano-size imprinting stamp is recovered. Finally, there is a need for an imprint stamp including features having a feature size that is less than a minimum feature size of a lithographic system that is used in fabricating the imprint stamp.